1. Field of the Invention
The present invention relates to a novel system for folding solar panels and to stabilizing means for the latter.
2. Description of the Prior Art
One of the principal conditions required of solar panels of large size planned for the future is represented by their ability to be folded up before returning to earth or before an important operation in orbit.
In the prior art, until now, two types of flexible solar panels have been used:
panels of the wound type and PA1 panels of the accordion type.
Solar panels of the wound type are wound around a drum which can only be fixed to the launching vehicle at two different points, that is to say at the two ends of the axle of the drum, which leads to instability. By reason of the absence of other fastening points, the size of this flexible solar panel is limited and, consequently, the power generated by such a panel is generally less than 5 KW.
As regards accordion type solar panels, they can be stored in a box which can easily be fixed to the launching vehicle.
Solar panels in accordion form can comprise three types of folding systems:
discontinuous panels with piano hinges; PA0 continuous panels folded at regular intervals and PA0 a combination of the two foregoing systems known as a "hybrid system".
The first folding system which uses piano hinges is not reliable since it requires a very large number of moving parts. Furthermore, it is difficult to repair since each sub-panel introduces a discontinuity into the electrical wiring. Also, the thickness of the hinges is difficult to adapt to that of the support panel, which is only a few microns thick, which results in the positioning of a complicated electrical installation and imparts risks to the use of ultra-thin cells.
The second folding system, which uses a continuous panel, exhibits difficulties which are essentially due to the fact that the fold loses its memory as a result of the numerous stresses that it undergoes in practice; and the fold is not stable when the support panel is placed under compression, which means that the support panel has locally a tendency to be folded back in reverse direction from that in which it should be folded. Such a tendency subjects the cells which are in the vicinity of the fold to very high stresses which can result in the rupture of the cells; and the environment causes permanent undulations along the fold line, which further increases the instability of the folding.
The third system, constituted by a non-continuous panel including piano hinges which connect different sub-panels together, each of the sub-panels being folded at regular intervals, possesses in spite of the fact that it facilitates manufacture and integration of the panel the drawbacks of the two preceding systems.
It is accordingly an object of the present invention to provide a system of folding solar panels which responds to the the necessities of practice better than the folding systems proposed according to the prior art.
It is notably an object of the invention to provide a folding system which is simple, which has high reliability since it does not require mechanical parts, and wherein the folding system enables the construction of solar panels without size limitations.
It is another object of the invention to provide a folding system for solar panels which enables electric power of 25 KW-50 KW to be attained, which will be necessary for future space uses.
It is another object of the invention to provide flexible solar panels provided with a folding system according to the invention which is adaptable to flexible solar panels designed in accordance with the arrangements of the prior art.